"High frequency" I-V curves for GaAs MESFETs through unique determination of small signal circuit parameters at multiple bias points

"High frequency I-V" can be calculated from integrating the bias dependent r.f. transconductance gm _RF and channel conductance gds _RF in the Vgs and Vds voltage plane. To obtain circuit elements from S-parameters fitting produces uncertainty in the circuit elements. An approach to uniquely determine each circuit element from the measured S-parameters is used to obtain a high frequency I-V curve for uniformly-doped MESFETs. No d.c. measurements are used in this approach because a circuit element obtained from d.c. measurement might be different from its r.f. counterpart. The small signal equivalent circuit used has eight bias dependent intrinsic elements and six bias independent extrinsic elements. Thus, gain compression and power saturation caused by the knee voltage and maximum channel current can be accurately modelled through the obtained high frequency I-V curve because the small signal equivalent circuit is valid in both the linear and saturation I-V regions.